Method and means for generating multiline sweep patterns



H. LIFSCHUTZ Filed March 21, 1942' FIRST WA E FOURTH WA VE THIRD WA VETIME L/M/ TE R CIRCUIT SAW- 7007/! GENERA 7' 0R SAW- TOOTH GENERATORSECOND WA vs IRST WA VE TIME llll 1 June 18, 1946.

l/VPU? 5 n A H m a u H D FROM m m m m a Patented June 18, 1946 UNITEDSTATES PATENT ore-ice METHOD AND MEANS FOR GENERATING MULTILINE SWEEPPATTERNS Harold Lifschutz, Washington, D. 0., now by judicial change ofname Harold Lyons Application March 21, 1942, SerialNo. 435,723

(Cl. 315-2d) (Granted under the act of March a, 1883, as amended April30, 1928; 370 0. G. 157) 11 Claims.

number of sweep lines desired. The sweep lines produced in the foregoingmanner will not be horizontal with respect to the vertical deflectionplates of the oscillograph, and when pulses are applied to the verticaldeflection plates in synchronlsm with the sweep, the pulse indicationson the lines of the sweep pattern are not at right angles thereto.

Sweep circuits are provided in the prior art for generating horizontalmulti-line sweep patterns in which pulse indications are produced atright angles to the sweep lines. In these systems, saw tooth wave formsare applied to the horizontal deflection plates of an oscillograph,while a, complex wave form is simultaneously applied to the verticaldeflection plates in phase with the voltage applied to the horizontalplates. The complex wave form provides application of constant voltageto the vertical deflection plates during the time that each saw-toothwave form applied to the horizontal plates propagates from a minimum toa maximum value, or during the period of each wave when the sweep linesof the pattern are generated. Such a wave form is so characterized thatthe values, or the amplitudes of the constant voltage portions of thewave. progressively decrease upon application of each cycle of saw-toothwave forms to the horizontal plates. The application of, such wave formsto the deflection plates of an oscillograph produce a multiline sweeppattern in which the individual lines of the pattern are horizontal andare separated from each other by distances corresponding to theprogressive reduction in amplitude of the constant voltage portions ofthe complex wave. However, extreme difliculties have been encounteredwhen attempting to generate a complex wave form of the foregoing type,since the problems relating to the generation of square wave forms areinvolved. For example, the wave tends to overshoot when an abrupt changefrom one constant voltage to the next constant voltage of a loweramplitude is attempted, while difliculties have also arisen whenendeavoring to cause such abrupt changes in voltageto occur at a highrate of speed. In view of these imperfections the sweep lines of thepatterns produced in the foregoing manner are distorted, especially atthe beinning of each horizontal line. The latter re sult is particularlydisadvantageous, since in practically all applications ofmulti-linesweep patterns, it is necessary that the individual sweeplines be undistorted and linear at the beginning thereof.

It is therefore an object of the present invention to provide a novelmethod for generating a horizontal multi-line sweep pattern.

Another object is to provide novel means for generating horizontalmulti-line sweep pattern.

Another object is to provide means responsiveto saw-tooth wave form; forproducing a horizontal multl-line sweep pattern on an oscilloraph.

Another object is to provide a sweep circuit for applying saw-tooth waveforms to the deflection plates of an oscillograph, with means applyingthe wave forms to the horizontal deflection plates at a. frequency anumber of times greater than the frequency of the saw-tooth wave formsapplied to the vertical deflection plates equal to a number of sweeplines desired, while also including means for producing each sweep linein such a manner during a. certain period,

that the voltage applied to the vertical deflection plates during suchperiod is substantially constant.

Still another object of the present invention is to provide a novelsweep circuit for producing a multi line sweep pattern on anoscillograph which includes means applying saw-tooth wave forms to thehorizontal deflection plates of they oscillograph at a frequency anumber of times greater than the frequency of the saw-tooth wave formsapplied to the vertical deflection plates that is equal to the number ofsweep lines desired, with means limiting the linearly varying voltage ofeach of the saw-tooth wave forms applied to the horizontal plates sothat the sweep lines are produced during a period of time whensubstantially constant voltage is applied to the vertical deflectionplates.

Still another object is to provide a sweep circult of the abovecharacter including mean responsive to a certain voltage value of thesawtooth wave forms applied to the horizontal plates for maintainingeach wave form at a constant voltage value following said certain voltae for reducing the portion of each wave form that is capable oiproducing a sweep line whereby each 3 sweep line is generated during aperiod of time wherein substantially constant voltage is applied to thevertical deflection plates.

Other objects and features of the invention will appear more fully fromthe following detailed description when considered in connection withthe accompanying drawing which discloses one embodiment of theinvention. It is to be elfpressly understood, however, that the drawingis designed for purposes of illustration only and not as a definition ofthe limits of the invention, reference for the latter purpose being hadto the appended claims.

In the drawing, wherein similar reference characters denote similarelements throughout the several views:

. 4 applied to the horizontal deflection plates from generator III inorder to generate each sweep line during a period of time during whichnegligible progress takes place in the linearly progressive portion ofthe wave form applied to the vertical deflection plates. As shown inFig. 1, such means comprises limiter circuit I! which functions to limitthe saw tooth waveforms of generator l Fig. 1 is a block diagram of asweep circuit embodying the principles of the present invention;

Fig.- 2 shows the type of wave form applied to the horizontal deflectionplates of the oscillograph disclosed in Fig. 1;

Fig. 3 shows a type of wave form applied to the vertical deflectionplates of the oscillograph disclosed in Fi 1;

Fig. 4 is a schematic showing of the limiter circuit disclosed in Fig.l, and

Fig. 5 is a diagrammatic illustration of the sweep pattern'produced bythe circuit shown in Fig. l.

With reference more particularly to Fig, 1 of the drawing, a sweepcircuit for producing a horizontal multi-line sweep pattern is disclosedtherein including a pair of saw-tooth wave generators I n and II ofconventional construction. Generator I 0 is adapted to produce saw-toothwave forms in accordance with a synchronizing source, such as a sourceof equally spaced electrical impulses, applied thereto from inputtermina1 l2. Generator II is likewise adapted to generate saw-tooth waveform in response to application of the synchronizing source fromterminal l2; however, the frequency of the sawtooth wave output ofgenerator II is adapted to be a certain number of'times less than thefrequency of the output of generator III that is equal to the number ofsweep lines that is desired in the pattern. In order to accomplish theforegoing, a suitable frequency divider I3 is positioned between inputterminal I2 and saw-tooth wave generator II in order to reduce thefrequency of the synchronizing source a sufllcient amount to causeoperation'of generator H in the'manner noted heretofore. Frequencydivider l3 may be of conventional construction, such as a frequen-- cydivider comprising a plurality of electronic counter circuits of thescale-of-two type for producing an output pulse upon application ofevery certain number of input pulses thereto from terminal l2. Theoutput of generator in is fed to horizontal deflection plates l1 and isof oscillograph 16, while the saw-tooth wave forms from generator I 0are applied to the vertical deflection plates I1 and I8. It is to beunderstood that the terms vertical and horizontal are relative and maybe interchanged without change in results.

As stated heretofore, it is one of the objects of the present inventionto provide a sweep circuit having novel means which operates to producea pattern on oscillograph l6, which includes a plurality of horizontalsweep lines,'upon application of the outputs of saw-tooth wavegenerators i0 and II. More particularly, such means functions to reduceor limit the linearly increasmg voltage portion of each saw-tooth waveform .in a manner noted above and to apply the resultant wave forms tohorizontal deflection plates l1. and I8. Limiter circuit is may beconstructed in numerous ways to limit the output of saw-tooth wavegenerator III; as shown in Fig. 4 for example, the circuit may include adiode vacuum tube 20 which is normally in a non-conducting state butwhich is biased in such a manner, by means of resistance 2| and biassupply 22, as to be rendered conducting when each wave of the saw-toothvoltage rises to a certain potential to thus maintain the remainingportion of the saw tooth wave, which normally linearly increases, atconstant voltage. The output of limiter circuit i9 is shown in Fig. 2,It can be readily seen from this figure that the voltage of eachsaw-tooth wave form linearly increases from zero potential until point ais reached, at which instant limiter circuit l9 functions to maintainthe remaining portion of each wave at constant voltage.

Operation of the sweep circuit disclosed in Fig. 1 may be more readilyunderstood with reference to Fig. 2, when considered in connection withFig. 3 of the drawing which latter discloses the voltage applied to thevertical deflection plates 14 and It. From Figs. 2 and 3 it can bereadily seen that the output of generator 10 is at a frequency fourtimes greater than the frequency of the saw-tooth wave forms produced atgenerator II, in order to produce a sweep pattern having four horizontallines. It is to be expressly under- 0 stood, however, that frequencydivider I: may be liU adjusted to reduce the frequency of generator IIany desired amount, with respect to generator I 0, to thus obtain anydesired number of sweep lines on the oscillograph pattern. Also, itcan'be readily seen from Figs. 2 and 3 that the saw-tooth wave formsapplied to the horizontal and vertical deflection plates are insynchronism with each other, with the above mentioned frequency ratio.The first sweep line of the pattern is generated when the voltage of thefirst wave form shown in Fig. 2 linearly increases from zero potentialto a certain value designated at point a, during which time negligibleyariation takes place in the voltage applied to deflection plates I land I5 since the saw-tooth wave shown in Fig. 3 has propagated for avery short period of time with respect to the complete cycle thereof.When the first wave form of Fig. 2 reaches point a, limiter circuit l8functions to maintain the remaining period of the wave at constantvoltage until the wave is terminated. As shown in Fig. 5, the foregoingproduces sweep line b which is substantially horizontal. Sweep line b isgenerated during the period c of linearly increasing voltage of thefirst wave form shown in Fig. 2. The period d of constant voltage acrossthe horizontal deflection plates permits production of a vertical lineextending downwardly from the end of sweep b during period d, while theabrupt drop to zero potential, to terminate the wave form. causes thecathode ray beam to move to a position suitable for the initiation ofthe next sweep line. During propagation of the first wave, the sawtoothwave shown in Fig. 3 propagates in synchronism therewith, to thus applya linearly increasing beam-depressing potential to the verticaldeflection plates so that the next sweep line a. generated during theperiod of linearly increasing voltage c' of the second wave form of Fig.2, occupies a position below the sweep line b. As the 2d. id-Md 4th waveforms shown in Fig. 2 propagate. sweep lines b, i and g are produced onthe screen of oscillograph l6, as shown in Fig. 5. Since substantiallyconstant voltages are applied to vertical deflection plates II and itduring the periods 0 of linearly increasing voltage across thehorizontal deflection plates, the-sweep lines generated by the latterare substantially horizontal. When pulses are appliedto the verticaldeflection plates in synchronism" with the wave forms shown in Fig. 2,pulse indications are produced on the sweep lines b, e, 1 ii it" thatare at right angles thereto, as shown in Fig. 5.

The sweep lines produced in accordance with the principles of thepresent invention may be caused to occupy substantially true horizontalposition, by increasing the period d, of constant voltage, of each ofthe wave forms with respect to the period c, of linearly increasingvoltage, shown in Fig. 2. Also. if desired. the sweep lines may becaused to deviate from the substantially true horizontal position byincreasing the period 0 while decreasing a period of constant voltage(1.

There is thus provided by the present invention novel method and meansfor producing a horizontal multi-line sweep pattern on an oscillograph.Such means employs the application of saw-tooth wave forms and therebyproduces a pattern having undistorted sweep lines since sawtooth waveforms may be readily generated. In order to generate a horizontalmulti-line sweep pattern by utilization of saw-tooth wave forms, meansare provided herein for reducing the linearly increasing voltage portionof the saw-tooth wave forms applied to the horizontal deflection plates,thus decreasing the portion of each sawtooth wave form which produces asweep line. so that the propagation of the saw-tooth wave form, of aless frequency, applied to the vertical deflection plates, is veryslight with respect to the complete cycle of such wave. to thereby applysubstantially constant voltage to the vertical de- {lection platesduring generation of each sweep ine.

Although only one embodiment of the invention has been disclosed anddescribed in detail herein, it is to be expressly'understood thatvarious changes and substitutions may be made therein without departingfrom the spirit of the invention as well understood by those skilled inthe art. Reference therefore will be had to the appended claims as adefinition of the limits of the invention.

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

What is claimed is:

l. The method of generating a horizontal multi-line sweep pattern on anoscillograph which comprises applying lineal saw-tooth wave forms to thevertical deflection plates of the oscillograph, applying linealsaw-tooth wave forms to the horizontal deflection plates at a frequencya number of times greater than the frequency of the saw-tooth wave formsapplied to said vertical plates and equal to the number of sweep linesdesired, and limiting the linearly increasing voltage portion of each ofthe wave forms applied to the horizontal deflection plates whereby s eeplines are produced on. the oscillograph during a period of time when buta small fraction of the variation in voltage across the verticaldeflection plates takes place.

2. The method of generating a horizontal multi-line sweep pattern on vanoscillograph which I comprises producing a first source of saw-toothwave forms each having a linearly varying voltage portion, producing asecond source of saw-tooth v wave forms each having a linearly varyingvoltage portion at a frequency a number of times greater than thefrequency of said first source that is equal to the number of sweeplines de-' the complete period of each wave, and applying the saw-toothwave forms from the second'source to the horizontal deflection plates ofthe oscillograph whereby the sweep lines are produced dur ing periods oftime wherein a substantially negligible variation takes place in thevoltage applied to the vertical deflection plates.

3. The method of producing a horizontal multi-line sweep pattern on anoscillograph which comprises generating a first source of saw-tooth waveforms, each having a linearly varying voltage portion, producing asecond source of saw-' tooth voltage forms each having a linearly vary-(ill ing voltage portion at a frequency a number of times greater thanthe frequency of said first source that is equal to the number of sweeplines desired, applying said first source of 'said sawtooth wave formsto the vertical deflection plates of the oscillograph, limiting theoutput of the saw-tooth wave forms from said second source for ti-linesweep pattern on. an oscillograph which comprises producing a firstsource of saw-tooth wave forms having a linearly varying portion,providing a second sourceof saw-tooth wave forms having a linearlyvarying portion at a frequency a number of times greater than the fre- Yquency of said first source that is equal to the number of sweep linesdesired, applying said first source of said saw-tooth wave forms to thevertical deflection plates of the oscillograph, passing the output ofsaid second source through a limiter circuit for limiting the largerportion of each wave form to a substantially constant voltage andpermitting substantially the entire remaining and smaller portion tovary substantially linearly, whereby the linearly varying voltageportion of each wave comprises a substantially short period ith respectto the complete period of each wave, and applying the output of thelimiter circuit to the horizontal deflection plates of the oscillographfor producing horizontal sweep lines thereon during a period of timethat is comparatively short with respect to the complete period of thesaw-tooth wave forms applied'to the vertical deflection plates wherebythe voltage applied to the vertical deflection plates can vary 7 onlyslightly during the period of generation of each sweep line.

5. A method of generating a. horizontal multi-line sweep pattern on anoscillograph which comprises applying saw-tooth wave forms to thevertical deflection plates of the oscillograph, simultaneously applyingother wave forms to the horizontal deflection plates of the oscillographat a, frequency a number of times greater than the frequency of said sawtooth wave forms equal to the number of sweep lines desired, the saidother wave forms applied to the horizontal deflection plates each havinga portion of linearly increasing voltage comprising a short portion ofthe cycle with substantially the entire remaining larger portion ofconstant voltage, and causing the linearly increasing voltage portionsof each wave to produce a sweep line on the oscillograph, with thevoltage applied to the vertical deflection plates being substantiallyconstant throughout generation of each sweep line.

6. A method of generating a multi-line sweep pattern on an oscillographwhich comprises producing a source of wave forms each of which comprisea portion having linearly varying voltage. applying said wave forms at afirst frequency to the vertical deflection plates of the oscillograph,simultaneously applying said wave forms at a frequency a number of timesgreater than said first frequency equal to the number of sweep linesdesired to the horizontal deflection plates of the oscillograph, andreducing the duration of the linearly varying voltage portion of thewave forms applied to the horizontal plates to a small portion of thecycle of said wave for generating sweep lines during a period whereinsubstantially negligible variation takes place in the voltage applied tothe vertical deflection plates.

7. A circuit for generating a horizontal multiline sweep pattern on anoscillograph comprising means applying saw-tooth wave forms each havinga, linearly varying voltage portion to one pair of deflection plates ofthe oscillograph, means applying saw-tooth wave forms each having alinearly varying voltage portion to the other pair of deflection platesat a frequency a number of times greater than the frequency of the sawtooth wave forms applied to said one pair that is equal to the number ofsweep lines desired, and means limiting the linearly varying voltageportion of each of the saw-tooth wave forms applied to said other pairof deflection plates to a small portion of the wave cycle andmaintaining the voltage constant for substantially the entire remainingportion of the cycle, whereby sweep lines are produced each during asmall portion of the lineal portion of said first wave.

8. A circuit for generating a. horizontal multiline sweep pattern on anoscillograph comprising a first source of saw-tooth wave forms eachhaving a linearly varying voltage portion, a second source of saw-toothwave forms each having a linearly varying voltage portion and of afrequency a number of times greater than the frequency of said firstsource that is equal to the number of sweep lines desired, meansapplying said first source to the vertical deflection plates of theoscillograph, means maintaining a continuous and greater portion of eachsaw-tooth wave form of said second source at constant voltage wherebythe remaining linearly increasing voltage portion of each wave formcomprises a short period of time with respect to the complete period ofeach wave, and means applying the saw-tooth wave forms of said secondsource to the horizontal deflection plates or the oscillograph wherebythe sweep lines are produced during periods or time wherein negligiblevariation takes place in the voltage applied to said vertical deflectionplates.

9. A circuit for generating a horizontal multiline sweep pattern on anoscillograph comprising a first source of saw-tooth wave forms eachhaving a linearly varying voltage portion, a secand source of saw-toothwave forms each having a linearly v ryin voltage portion and of afrequency a number of times greater than the frequency of said firstsource that is equal to the number of sweep lines desired, meansapplying said first source to the vertical deflection plates of theoscillograph, means limiting the output of said second source ofsaw-tooth wave forms for limiting the linearly varying voltage portionsthereof, and means applying the limited wave forms to the horizontaldeflection plates of the oscillograph for applying a linearly increasingvoltage thereto during a period of time wherein substantially constantvoltages are applied to said vertical deflection plates.

10. A circuit for generating a horizontal multi-line sweep pattern on anoscillograph comprising a first source of saw-tooth wave forms eachhaving a linearly varying voltage portion, a second source of saw-toothwave forms each having a linearly varying voltage portion and of airequency a number of times greater than the irequency of said firstsource that is equal to the number of sweep lines desired, meansapplying said first source to the vertical deflection plates of theesciliograph, a limiter circuit for maintaining a continuous and greaterportion of each wave forms from said second source at constant voltagewhereby the entire remaining linearly varying voltage portion of eachwave comprises a substantially short period with respect to the completeperiod of each wave, and means applying the output of said limitercircuit to the hori zontal deflection plates of the oscillograph forapplying linearly increasing voltages thereto during a period of timethat is substantially short with respect to the complete period of thesawtooth wave forms applied to said vertical deflection plates wherebynegligible variation takes place in the voltage applied to said verticalde iiection plats during the period of generation of each sweep line.

11. A circuit for generating a horizontal multi-line sweep pattern on anoscillograph comprising means applying saw-tooth wave forms to thevertical deflection plates of the oscillograph, means for simultaneouslyapplying other wave forms to the horizontal deflection plates of saidoscillograph at a frequency a number of times greawr than the frequencyof said saw-tooth wave forms equal to the number of sweep linesdesired,said other wave forms having a portion of linearly increasing voltagefollowed by a portion of constant voltage with the portion of linearlyincreasing voltage comprising a short portion of the cycle of each wavewith respect to the portion of constant voltage, and said linearlyincreasing voltage portions producing a sweep line on the osciliographduring a period of time wherein negligible progress takes place in thelinearly progressive portion of the wave form applied to said verticaldeflection plates.

HARDID' LIFSCHUTZ.

